This invention relates to an operating mechanism for high current switches which are positioned side by side or back to back, particularly load-break bolted pressure contact switches where it is necessary or desirable to operate the switches alternately, that is, to close one switch while maintaining the other switch in its open condition or to open one switch while maintaining the other switch closed.
Load-break bolted pressure contact switches are frequently used as service entrance equipment and in other relatively high current applications. Typically, switches of this type may be used in multi-pole switching operations requiring interruption under loads of currents of the order of 400 to 6,000 amperes. Frequently, these switches are positioned side by side or back to back. In such switches, it is critically important that the contacts open and close rapidly to minimize arcing and thereby avoid pitting and deterioration of the contact members. Most switches of this kind are provided with a latching mechanism for each pole of the switch to secure the contacts in closed position and to prevent any accidental opening of the switch due to external shocks or other factors. The switch blades are relatively heavy and the mechanical forces involved in opening and closing of the switch may be substantial.
Rapid opening and closing of the switch contacts is accomplished by an overcenter toggle spring mechanism which accelerates the speed of opening and closing of the switch contacts. Spring mechanisms of this type are actuated by lost motion mechanisms operatively connected between an operator's shaft and the switch contacts. These lost motion mechanisms provide manual opening of the switch contacts to a point at which disengagement is almost achieved, followed by a rapid spring actuated movement of the switch blade clear of the fixed switch contacts in order to minimize arcing.
Co-ordinated actuation of two high-current switches has not been practical with previously known mechanisms.